This invention relates generally to a heat exchanger or more explicitly to a circular recuperator and more particularly to an apparatus and method for assembling the circular recuperator.
Many gas turbine engines use a heat exchanger or recuperator to increase the operation efficiency of the engine by extracting heat from the exhaust gas and preheating the intake air. Typically, a recuperator for a gas turbine engine must be capable of operating at temperatures of between about 500 degrees C. and 700 degrees C. and internal pressures of between approximately 450 kPa and 1400 kPa under operating conditions involving repeated starting and stopping cycles.
Many recuperators are of a primary surface construction. In a primary surface recuperator, a plurality of sheets are stacked in a spaced apart configuration to form a cell. The spacing therebetween form a plurality of donor passages and a plurality of recipient passages. In many operations, the hot exhaust gas is passed through the donor passages and an atmospheric temperature intake air is passed through the recipient passages. Heat from the hot exhaust is transferred through the sheet and absorbed by the cooler intake air. Thus, thermal energy from the exhaust gas is extracted and conducted to the intake air increasing the efficiency of the engine.
In many applications the primary surface sheet used in forming the cell is very thin, flimsy and difficult to maintain a uniform cross sectional area of the passages between sheets. To enhance the rigidity of the thin sheets, the sheets are formed into an accordion type configuration forming peaks or crests and valleys forming a plurality of upwardly and downwardly opening, transversely extending, relatively deep grooves being relatively closely spaced and having substantially vertical side walls or fins. In forming a recuperator using such sheets, the peeks of alternate sheets are aligned and the valleys of alternate sheets are aligned to form the donor passages and the recipient passages. Additionally, many of the sheets are formed with a serpentined configuration to enhance a controlled turbulent which increases heat conductivity and resulting efficiency. In manufacturing such recuperators, the component parts are fixedly attached together by a welding process to prevent leakage from the respective donor passages and recipient passages.
U.S. Pat. No. 5,060,721 issued on Oct. 29, 1991 to Charles T. Darragh discloses an example of one such recuperator. The recuperator disclosed in this patent has a circular configuration. The recuperator has a plurality of cell made from a pair of primary surface sheets, a plurality of spacer bars and a plurality of guide strips. The component parts are welded together to form the recuperator. The welding of these thin sheet and component parts into a cell having a sealed interface is difficult to accomplish in a cost effective and efficient manner.
During the assembly of the cells and the recuperator, the interface of the components are positioned one with respect to another in a preestablished relationship and are welded together. The effectiveness of the positioning and holding process during the welding process used to form the cells is in many instances dependent on the ability to maintain the relationship of the components one to another. The result of maintaining the components relationship may results a defective weld and thus a defective recuperator. For example, in positioning of the cells the components relationship can result in an excessive gap or misalignment. Thus, the resulting weld can be defective and leakage between adjacent cells can occur. Thus, an effective and efficient process is needed to insure the position and location of the component relationship to insure a functional recuperator.
The present invention is directed to overcome one or more of the problems as set forth above.
In one aspect of the invention an apparatus for manufacturing a recuperator core is disclosed. The recuperator core is made from a plurality of components. The plurality of components include a plurality of cells and an inner sealing member having a first end and a second end. The apparatus has a lower or inner chucking portion being movable between a lower position and an upper position. The lower or inner chucking portion is movable between a retracted position and an expanded position. And, the lower or inner chucking portion positions the inner sealing member relative to the plurality of cells. An upper portion is positioned about the lower or inner chucking portion and defines a first side and a second side. The upper portion is rotatable between a first position having the first side up and a second position having the seconds side up. The upper portion is movable between a loading position and a clamping position. And, the upper portion positions the plurality of cells relative to the inner sealing member. And, a welding portion defines a first weld positioned at an interface of the first end of the inner sealing member and the plurality of cells and a second weld positioned at an interface of the second end of the inner sealing member and the plurality of cells.
In another aspect of the invention a method of manufacturing a recuperator core is disclosed. The recuperator core includes a plurality of cells and an inner sealing member having a first end and a second end. The method of manufacturing the recuperator core has the steps of: positioning a lower or inner chucking portion in an upper position; aligning the first end of the inner sealing member with an end of the lower of inner chucking portion; expanding the lower or inner chucking portion into an expanded position; positioning an upper portion in a first position and in a loading position; placing a preestablished quantity of the plurality of cells in the upper portion; moving the upper portion from the loading portion into at least one of a low pressure clamping position, a medium pressure clamping position and a high pressure clamping position; aligning the plurality of cells into a preestablished configuration; welding an interface of the plurality of cells and the first end of the inner sealing member; rotating the upper portion into a second position; welding an interface of the plurality of cells and the second end of the inner sealing member; retracting the lower or inner chucking portion from the expanded position to a retracted position; moving the upper portion from the one of the low pressure clamping position, the medium pressure clamping position and the high pressure clamping position into the loading position; and removing the manufactured recuperator core.
In another aspect of the invention a manufacturing system is adapted for making a finished circular recuperator core. The recuperator core defining an axis xe2x80x9cAxe2x80x9d and is make up of a plurality of finished cells and an inner sealing member. The inner sealing member or ring has a circular configuration and defines a first end and a second end. The manufacturing system has an input end having a supply of the plurality of finished cells provide thereto. An assembly station has a table and defines an axis coinciding with the axis xe2x80x9cAxe2x80x9d of the circular recuperator core during the manufacturing of the recuperator core. The table includes a lower or inner chucking portion having an axis coinciding with the axis xe2x80x9cAxe2x80x9d and is movable between a lower position and an upper position. An upper portion is positioned about the lower or inner chucking portion and has a stacking portion being movable between a loading position and a clamping position. The upper portion is rotatable between a first position and a second position. A welding station is operatively connected to the assembly station. The welding station is capable of performing a tack welding operation and a lineal welding operation. An output end has a location for placing the finished circular recuperator core after the assembly and welding thereof.